The present invention relates to a device for the batch-wise preparation of loose material and more particularly, a device comprising a horizontally arranged drum and an impact rotor concentric to the drum axis provided with beating blades.
A device as aforesaid is known from DE-C2-29 09 408 in which the impact rotor has beating blades with a straight outer peripheral side. Beating blades of this type are of simple construction but their abrasive effect and hence also the regeneration effect of old sand is unsatisfactory.
It is the object of the present invention to produce a device of the above-mentioned type whose impact rotor is constructed so that it has the best possible abrasive effect with a low power consumption for the rotor drive.